Propeller blade assembly

ABSTRACT

A propeller blade assembly having a propeller blade having a leading edge, a trailing edge, and a tip edge extending between the leading and trailing edge, a replaceable guard selectively mountable to the propeller blade to cover at least the leading edge, and multiple fasteners selectively coupling the replaceable guard to the propeller blade.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. §119 to British Patent Application No. 13171012, filed Sep. 26, 2013, the disclosure of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

Contemporary vehicles, such as hovercrafts, may include propeller blades to provide propulsive force. The propeller blades may be exposed to environments that erode portions of the propeller blades. Propeller failures may be caused by sand and stone nicks to the leading edge.

BRIEF DESCRIPTION OF THE INVENTION

In one aspect, an embodiment of the invention relates to a propeller blade assembly, having a propeller blade having a leading edge, a replaceable guard selectively mountable to the propeller blade to cover at least the leading edge, and multiple fasteners selectively coupling the replaceable guard to the propeller blade and wherein at least one of the multiple fasteners does not extend beyond an exterior of the replaceable guard.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a schematic embodiment of an environment in which a propeller blade assembly may be used.

FIG. 2 is a top view of a propeller blade assembly according to an embodiment of the invention.

FIG. 3 is a cross-sectional view of a portion of a propeller blade assembly according to an embodiment of the invention.

FIG. 4 is an alternative cross-sectional view of a portion of the propeller blade assembly of FIG. 3.

FIG. 5 is a cross-sectional view of a portion of a propeller blade assembly according to another embodiment of the invention.

DESCRIPTION OF EMBODIMENTS OF THE INVENTION

FIG. 1 schematically illustrates a vehicle, more specifically a hovercraft 8, in which a propeller blade assembly 10 may be used. It will be understood that the propeller blade assembly 10 may be used in any suitable vehicle and hovercraft. FIG. 2 illustrates a propeller blade assembly 10 having a propeller blade 12, a replaceable guard 14, and multiple fasteners 16. The propeller blade 12 may have an airfoil configuration. The propeller blade 12 may include a front surface 20 and a rear surface (not shown) bounded by a leading edge 22, a trailing edge 24, and a tip edge 26, which extends between the leading edge 22 and the trailing edge 24.

The replaceable guard 14 may be selectively mountable to the propeller blade 12 to cover at least the leading edge 22 of the propeller blade 12. In the illustrated example, the replaceable guard 14 covers the leading edge 22 and the tip edge 26. Further, the replaceable guard 14 has been illustrated as being multi-segmented although this need not be the case. In the illustrated example, two of the multiple segments are used to cover most of the leading edge 22 while a third is used to cover the tip edge 26. Alternatively, in a multi-segmented configuration, a first segment may cover the leading edge 22 and a second segment may cover the tip edge 26. It is contemplated that there may not be a replaceable guard 14 on the trailing edge 24.

The multiple fasteners 16 may selectively couple the replaceable guard 14 to at least one of the front surface 20 and the rear surface (not shown). At least one of the multiple fasteners 16 will not extend beyond an exterior of the replaceable guard 14. It is contemplated that all of the multiple fasteners 16 will not extend beyond an exterior of the replaceable guard 14. In the illustrated example, multiple fasteners 16 operably couple the replaceable guard 14 to both the front and rear surfaces of the propeller blade 12. More specifically, the multiple fasteners 16 alternate between the front and rear surfaces along a length of the propeller blade 12. While no fasteners 16 have been illustrated as attaching the replaceable guard 14 to the rear surface at the tip edge 26 of the propeller blade 12 it will be understood that fasteners 16 may attach the replaceable guard 14 to the rear surface at such a location.

FIG. 3 illustrates one example of a portion of a propeller blade, replaceable guard, and fastener, which may be used in a propeller blade assembly including the propeller blade assembly 10. As the propeller blade 112, replaceable guard 114, and fastener 116 are similar to those previously described, like parts will be identified with like numerals increased by 100, with it being understood that the description of the like parts of the propeller blade assembly 10 applies to the propeller blade assembly having the propeller blade 112, replaceable guard 114, and fastener 116, unless otherwise noted.

As with the earlier described embodiment, the propeller blade 112 includes a front surface 120 and a rear surface 118 as well as a leading edge (not visible), a trailing edge (not visible), and a tip edge 126. One difference is that the propeller blade 112 is illustrated as a composite body including a foam core 130, a carbon and glass fiber layer 132, and a polyurethane layer 134. It will be understood that the propeller blade 112 may be formed in any suitable manner from any suitable material(s). Further, a foam insert 136 has been illustrated as being located between a portion of the propeller blade 112 and the replaceable guard 114. An insert 140 may be bonded into a portion of the propeller blade 112 and sized to receive one of the multiple fasteners 116. In the illustrated example, a block 142 has been moulded within the propeller blade 112 and the insert 140 is bonded into the block 142. The block 142 may be formed from a composite such as a glass fiber and insert moulded into the propeller blade 112.

By way of non-limiting example, the replaceable guard 114 has been illustrated as including a backer layer 150 and an erosion protection rubber layer 152. It will be understood that the replaceable guard may be formed from any number of layers including a single layer. It will be further understood that the replaceable guard may be formed from any suitable material(s).

In the illustrated example, only a single fastener 116 has been illustrated; however, multiple fasteners may be included and may operably couple the replaceable guard 114 to the front surface 120 and/or the rear surface 118 of the propeller blade 112. The fastener 116 is illustrated as including a rivet 160 selectively receivable in the insert 140 and a washer 162. The replaceable guard 114 is clamped between the washer 162 and the insert 140 when the rivet 160 is received within the insert 140 and the fastener 116 does not extend beyond an exterior 164 of the replaceable guard 114. By way of non-limiting example, FIG. 4 illustrates the fastener 116 operably coupling the replaceable guard 114 to the rear surface 118.

FIG. 5 illustrates an alternative propeller blade 212, a replaceable guard 214, and a fastener 216. As the propeller blade 212, replaceable guard 214, and fastener 216 are similar to those previously described, like parts will be identified with like numerals increased by 100, with it being understood that the description of the like parts of the propeller blade assembly 10 and the propeller blade 112, replaceable guard 114, and fastener 116 applies to the propeller blade assembly having the propeller blade 212, replaceable guard 214, and fastener 216, unless otherwise noted.

One difference is that the fastener 216 has been illustrated as including a screw 260 that is at least partially threaded and sized to be threaded into the insert 240. Another optional difference is that the insert 240 may be at least partially threaded and has been illustrated as being fully threaded. As with the previously described embodiment the fastener 216 includes a washer 262 and when assembled, the replaceable guard 214 is clamped between the washer 262 and the insert 240 when the screw 260 is threaded into the insert 240.

The embodiments described above provide for a variety of benefits including that the embodiments above allow for an erosion protection guard to attach to at least a leading edge of a propeller blade in a manner that enables speedy replacement of an eroded guard using simple tools without damaging the propeller blade. In this manner, multiple guard changes may be made without replacement of the propeller blade and corrosion has no effect on its operation. In the above described embodiments, removal of the guard does not require any contact with the composite material of the propeller blade. Thus, the composite in the propeller blade will not be affected by guard fitting and removal. The internal insert spreads the clamping load of the rivet. Further, discontinuity with the airfoil is minimal as the fasteners are flush with or do not extend beyond an exterior of the replaceable guard. One contemporary design relies on the use of bolts with special nuts fitted from each side of a through bore in the propeller blade. The bolt heads and nuts extend above the guard and may corrode and erode making it difficult to remove them causing high replacement costs. In the above described embodiments, corrosion will have no effect and because the design is flush or below the guard erosion will be minimal.

To the extent not already described, the different features and structures of the various embodiments may be used in combination with each other as desired. That one feature may not be illustrated in all of the embodiments is not meant to be construed that it may not be, but is done for brevity of description. Thus, the various features of the different embodiments may be mixed and matched as desired to form new embodiments, whether or not the new embodiments are expressly described. All combinations or permutations of features described herein are covered by this disclosure.

This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims. 

1. A propeller blade assembly, comprising: a propeller blade having front and rear surfaces bounded by a leading edge, a trailing edge, and a tip edge extending between the leading and the trailing edge; a replaceable guard selectively mountable to the propeller blade to cover at least the leading edge; and multiple fasteners selectively coupling the replaceable guard to at least one of the front and rear surfaces wherein at least one of the multiple fasteners does not extend beyond an exterior of the replaceable guard.
 2. The propeller blade assembly of claim 1 wherein the multiple fasteners operably couple the replaceable guard to the front and rear surfaces of the propeller blade.
 3. The propeller blade assembly of claim 2 wherein the multiple fasteners alternate between the front and rear surfaces along a length of the propeller blade.
 4. The propeller blade assembly of claim 1, further comprising an insert bonded into a portion of the propeller blade and sized to receive one of the multiple fasteners.
 5. The propeller blade assembly of claim 4, wherein the propeller blade further comprises a glass fiber block molded therein and wherein the insert is bonded into the block.
 6. The propeller blade assembly of claim 4 wherein at least one of the multiple fasteners comprises a rivet selectively receivable in the insert.
 7. The propeller blade assembly of claim 6, further comprising a washer and wherein the replaceable guard is clamped between the washer and the insert when the rivet is received within the insert.
 8. The propeller blade assembly of claim 4 wherein at least one of the multiple fasteners comprises a screw that is at least partially threaded and sized to be threaded into the insert.
 9. The propeller blade assembly of claim 8, further comprising a washer and wherein the replaceable guard is clamped between the washer and the insert when the screw is threaded into the insert.
 10. The propeller blade assembly of claim 1 wherein the propeller blade comprises a composite body.
 11. The propeller blade assembly of claim 1 wherein the replaceable guard comprises a backer layer and an erosion protection rubber layer.
 12. The propeller blade assembly of claim 1 wherein the replaceable guard covers at least the leading edge and the tip edge.
 13. The propeller blade assembly of claim 1 wherein the replaceable guard is multi-segmented.
 14. The propeller blade assembly of claim 13 wherein a first segment covers the leading edge and a second segment covers the tip edge.
 15. The propeller blade assembly of claim 1 wherein all of the multiple fasteners do not extend beyond an exterior of the replaceable guard. 